The human eye in its simplest terms functions to provide vision by transmitting and refracting light through a clear outer portion called the cornea, and further focusing the image by way of the lens onto the retina at the back of the eye. The quality of the focused image depends on many factors including the size, shape and length of the eye, and the shape and transparency of the cornea and lens. When trauma, age or disease cause the lens to become less transparent, vision deteriorates because of the diminished light which can be transmitted to the retina. This deficiency in the lens of the eye is medically known as a cataract. The treatment for this condition is surgical removal of the lens and implantation of an artificial lens or IOL.
While early IOLs were made from hard plastic, such as polymethylmethacrylate (PMMA), soft, foldable IOLs made from silicone, soft acrylics and hydrogels have become increasingly popular because of the ability to fold or roll these soft lenses and insert them through a smaller incision. Several methods of rolling or folding the lenses are used. One popular method is an injector cartridge that folds the lenses and provides a relatively small diameter lumen through which the lens may be pushed into the eye, usually by a soft tip plunger, such as the one described in U.S. Pat. No. 4,681,102 (Bartell), which includes a split, longitudinally hinged cartridge. Similar designs are illustrated in U.S. Pat. Nos. 5,494,484 and 5,499,987 (Feingold) and U.S. Pat. Nos. 5,616,148 and 5,620,450 (Eagles et al.). Other cartridge designs include, for example, U.S. Pat. No. 5,275,604 (Rheinish et al.) and U.S. Pat. No. 5,653,715 (Reich et al.).
In these prior art systems, an IOL is provided in a lens case from which the IOL is transferred into an injector cartridge, such as by using forceps. However, the step of transferring the lens from the case to the injector cartridge can inadvertently result in damage to the IOL, as in the cases where the optic of the IOL is scratched by the forceps or the haptics are torn off of the IOL. An alternative approach is to provide a preloaded injector, such as the one described in U.S. Pat. No. 7,156,854 (Brown et al.). In this case, there is not a separate loading step. However, such integrated injector systems are entirely disposable, and they are not compatible with reusable handpieces. Yet another alternative is to use a preloaded lens transfer case that uses a mechanism to transfer the IOL into a cartridge. But the existing lens transfer cases involve relatively complicated mechanical transfer mechanism in order to keep the lens in the correct loading position and to make sure that the IOL is correctly transferred to the cartridge.